Perchlorate occurs naturally, but also used to make rocket fuel

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WASHINGTON — Traces of a chemical used to make rocket fuel among other applications have been found in organic milk in Maryland, green leaf lettuce grown in Arizona and bottled spring water from Texas and California, the Food and Drug Administration has reported.

What’s not clear is the significance of the data, collected by the FDA through Aug. 19.

Sufficient amounts of perchlorate, which also occurs naturally, can affect the thyroid, potentially causing delayed development and other problems.

But Environmental Protection Agency official Kevin Mayer called for calm, saying in an interview Tuesday: “Alarm is not warranted. That is clear.”

'Struggle' to determine toxicity“I think that it is important that EPA and FDA and other agencies come to some resolution about the toxicity of this chemical,” Mayer said. “That has been, frankly, a struggle for the last few years.”

The FDA found that of the various food items it tested, iceberg lettuce grown in Belle Glade, Fla., had the highest concentrations of perchlorate. The greens had 71.6 parts per billion of the compound, the primary ingredient in solid rocket propellant. Red leaf lettuce grown in El Centro, Calif., had 52 ppb of perchlorate. Most of the purified, distilled and spring bottled water tested around the nation tested had no detectable amount of perchlorate.

The FDA said in a statement that consumers should not change their eating habits in response to the test results, posted on the agency’s Web site last Friday.

It's not clear how much of the perchlorate might be in the ground naturally or how much might be from human uses of the chemical. The human uses likely transfer the perchlorate to food via irrigation, the FDA says.

Safe level standard being draftedThe testing comes as federal agencies try find how much perchlorate people are exposed to from food so they can determine whether action is needed to protect the public health. Federal agencies have been trying since the early 1990s to determine what level of perchlorate is safe.

The state of California, meanwhile, set a standard of no more than 10 ppb of perchlorate in drinking water. That was lowered to 6 ppb in drinking water to account for the chemical also lacing food, Mayer said.

A more conservative suggestion, in a draft from the EPA, would allow no more than 1 ppb of perchlorate in drinking water.

The FDA tested lettuce samples collected at farms and packing sheds and bottled water from retail stores. Raw milk samples came from a research facility in Maryland and other milk samples were obtained from retail stores.

“These data are exploratory and should not be understood to be a reflection of the distribution of perchlorate in the U.S. food supply,” the agency said in a statement. “Until more is known about the health effects of perchlorate and its occurrence in foods, FDA continues to recommend that consumers eat a balanced diet, choosing a variety of foods that are low in trans fat and saturated fat, and rich in high-fiber grains, fruits and vegetables.”